A REPORT TO THE SANGGUNIANG PANGLALAWIGAN NG ILOILO Rainwater Harvesting in IWRM for Climate Change Adaptation Project UNEP- IWMC-TAWMB, 2007-2008 By Jessica Calfoforo Salas, Project Manager
May 13, 2015
A REPORT TO THE SANGGUNIANG
PANGLALAWIGAN NG ILOILO
Rainwater Harvesting in IWRM for Climate Change Adaptation Project
UNEP- IWMC-TAWMB, 2007-2008
By Jessica Calfoforo Salas, Project Manager
Iloilo Province
Panay Island
Project Area: The Tigum Aganan Watershed
The Tigum-Aganan Watershed Area – 52,669 ha Population – 419,973 persons, 391 villages Rainfall, Rainy Season, 6 mos. – 1600 mm Rainfall, Dry Season, 6 mos. - 345 mm Overseeing Body - The Tigum Aganan Watershed
Management Board: Municipalities of Maasin, Alimodian, Cabatuan, Sta. Barbara, Pavia, San Miguel, Oton, Iloilo City, NIA, DPWH, PIA, MIWD, CPU, KSPFI, Irrigators’ Association, KAPAWA
CONCEPTUAL FRAMEWORK
Rainwater Potential
CommunityApplication
Annual Average RainfallDry Season RainfallRainy Season RainfallDry Season Rainfall – 50%Rainy Seaso Rainfall + 50%Average Annual Rainfall +/ - 50%
Protect Natural Storage: Old Growth Forest & Groundwater
Projections in Sub Basin 17, 14, 12, 10 and 6
GIS Maps
Sub-Basin
Maps
Mianas Micro Watershed:f forestedUpland agriculture: Alimodian, Cabatuan, Sta. BarbaraLowland agriculture: OtonPavia, Built Up areaIloilo City, Built up area
PROJECT
CONCEPT
FRAME
WORKProvide Man-made storage: in soil & cisterns
Natural Storage
Storage in Groundwater
Storage in Forest Soil
Storage inGround Water
Only 10% of the runoff
reaches the ground water
Maraget Sandstone aquifer
Recharge Dry Season Ave540 mm/year or .054m3
7,781.9 CMD
MIWD DATA EXTRACTION 2007 =
10,380 CMD
Max. 1 pump capacity @ 20 lps = 15,552 CMD.
Capacity of total present facility (9 pumps) = 205 lps
Outcrop area is 52.6 km2
Since MIWD is serving only 24% of the city population, it is possible that total actual extraction is far more than the recorded extraction of MIWD.
An example:
Ground Water Supply Condition “Although a relatively large amount of deep ground
water exists at the center of the Iloilo plain, its development has already exceeded the sustainable level.” p.15 JISRADP study
Low efficiency in MIWD wells indicates lowering ground water level (Engr. Calasara, MIWD Operations Manager).
“It would be difficult to develop the deep groundwater in the other area because of its low potential as investigated by the test well in the field survey.” p. 18 JISRADP study
Further studies may be needed to define the aquifer
STORAGE IN
FOREST SOILRain on
Land
Surface Runoff
Evaporate
Infiltrate
In Sub-surface soil
Through the soil profile
Trees at Maasin Watershed 90.6% survival rate at sub project
Issues:
Poor biodiversity
Mono-cropping in large areas: bamboo, mahogany, gmelina
Accelerated spread of invasive species
No cutting of harvestable stands in a plantation-8 to 12 yrs old
Drying of rivers & creeks during summer & drought
Observations Today
33-year old plantation
7-12 year old trees
Dry Busay Creek
Dry Bungol Waterfall
A Dry Fishpond
Witnesses to a Lost Swamp
Tigbaw, Kagang, Tabun-ak, Badyang
Influence of Ground Cover on Surface Runoff and Soil Loss
Taken from Study on Sediment Condition in the Jaro and Iloilo River Basins, Iloilo Flood Control Project. , DPWH. Fig. 4.2, p84.”
POLICY DIALOGUE AT IWMC
Revisited Assumptions and their Scientific Bases
Reference No. 1. Fact Sheet, Tree and Forest (Dept of Environment Conservation, New York State)
“Trees provide protection for our watersheds. The forest floor, to which trees add leaves and decaying
wood, acts as a sponge and store water. “If the forest floor is a SPONGE, a tree is a PUMP that
transpires water into air make rain for the land. “A medium-sized tree (40 to 50Ft tall) will drink 10,000
gallons of water from the soil in a growing season. “Forest soil 36-inches deep can absorb and hold as
much as 18 inches of rain, or nearly 1 million gal per hectare.
“A medium-sized tree (40 to 50Ft tall) will drink 10,000 gallons of water from the soil in a growing season.
“Baltimore City Watershed experimented with converting open areas to young pine forests. The result was a decline in water yield of 283,000 gallons per year.
If the forest floor is a SPONGE, a tree is a PUMP that transpires water into air make rain for the land.
Reference # 2. Media Release by Ellen Wilson, Jeff Haskins/ Coimbra Sirica at
Business Communications “Trees Overplayed as Solutions to World’s Water
Problems, Finds Sweeping Report from UK’s Tropical Forestry Research Programme
Misguided Views on Water Management Have Encouraged Major Investments in Water Resource Projects that are Ineffective or Counterproductive, says Report.
Calls on Policymakers to Design Water Projects Based on Scientific Evidence of Benefits.”
Reference # 3 Internet Postinghttp:/www.guardian.co.uk“Research Pours Cold Water on Moisture Conservation Role for
Forests.”
By Tim Radford, science editor
Friday, July 29, 2005, The Guardian
Reference # 4: Mallin Falkenmark, “Water Management and Ecosystems”Living with Change, TEC Background Papers No. 9. Global Water Partnership Technical Committee.“Motherhood statements on forests and water which are against scientific evidence:
Forests increase rainfall – Forests increase runoff – Forests regulate flows – Forests reduce erosion – Forests reduce floods.
“A more questioning attitude is advised. The challenge of Adaptive Management is to uphold two incompatible imperatives: Respect the ecosystem imperative and commit to a set of human livelihood imperatives”
Reference # 5 – Watershed Magazine, Jan-June, 2005 “Flip flop
Hydrology” by Albert Nauta Expert meeting led by Director Romeo T. Acosta (FMB-DENR, ) drafted joint statements which included:
“Plantation forestry or forest regeneration on grassland or crop will greatly reduce annual water yields (approx 400-700 mm/yr) due to their high water use.
“Forest clearing leads to increased annual water yield but seriously impairs infiltration opportunities. This is due to gradual soil degradation or extensive compacted areas.
Reference 6: GWP TEC # 9
Terrestrial ecosystems consumed 2/3 of the rainfall over the continents, a total of 71,000 km3/year and temperate and tropical forests/woodlands consume 40,000km3 of this or 56%. Other areas consuming rain are croplands, grasslands, swamps and marshes, tundra and desert and other systems.
Reference # 7. Calder, The Blue Revolution: Land Use and Water Resources Management. Earthscam, London, UK, 1999 The perception that forests are good for the
water environment and for water resources has grown out of observation that linked land degradation with less forest and rehabilitation and conservation with more forest.
Reference # 8. Savanije, “New Definition for Moisture Recycling and Relationships with Land-Use Changes in the Sahel” Journal of Hydrology, 1995.
Recommendations to Enhance Storage in Natural Forest
Understand forest soil Use natural Regeneration Assisted natural regeneration Rainforestation Protect biological diversity Protect forest from exotic and invasive
species Create buffer zones Study erosion pattern, protect rivers
INTEGRATION OF RAINWATER
HARVESTING
Steps Taken Rainwater Harvesting Project
UNEP & IWMC-TAWMB
GIS Mapping/ study of the rainfall and the land characteristics of the watershed
Stakeholders’ assembly and planning Identification of demonstration areas for
rainwater harvesting Integration of rainwater harvesting in the
municipal and provincial development plans.
Demo for Lowland agriculture
Demo for artificial recharge
Demo for forest enhancement
Demo for upland agriculture
Demo for household storage
Demo for Forested Area
Demo for Household Storage
Demo for Upland Storage
Demo for Lowland Storage
Demo for Built Up Area Storage
RWH Applications for the Maasin Watershed to Mitigate Impact of Exotic Tree Plantation
A Watershed Planted with Exotic Trees
May take 20 years for trees to stabilize and trees may stop drinking much water but no storage in forest soil may be formed due to inability of organisms to decay exotic leaves. (University of Minnesota, Cornell University & ESSC (Ateneo University opinions). Fast growing exotic species mature and die in 15 to 20 yrs
Plantation creates dry soil. Rainwater ponds could help enrich soil and help growing trees in commercial plantation
Water pits
Rainwater Harvesting Technology
Some types of rainwater catchment facilities
Natural Depression
Infiltration ponds & canals
Dry Pond
Detention Ponds
Camilo Sacupon
Rainfed farm:
Yield – 120 sacks/cropping x 3 cropping or 6 tons a year for 2 hectares. NIA average is 3.3 tons/hectare
With 1,250 m2 mother tank and 100 m2 daughter tank, water can support 3 cropping of rice in a 2 ha. service area.
Andres Calfoforo Jr.
Yield of 1.5 ha., 120 sacks / ha. or 6 tons for 1.5 hectares
With 2,500 sq.m pond, water can support 3 croppings of rice and other selected crops such as pepper, tomatoes, etc.
NIA’s cost to provide irrigation to 1 hectare of riceland is P250,000 to P600,000 / hectare
Income Diversification
Artificial Recharge
Potential Benefits of IntegratingRainwater Harvesting
Retains and stores rainwater during rainy season Helps mitigate flooding: urban & rural Reduces use of processed public system water Reduces use of river stream flow to allow
downstream use Recharges shallow ground water A tool for managing water demand
IMPACT ofEXTREME WEATHER
VARIABILITY
Extreme weather; major disasters
Increase in frequency and magnitude 76% of the 100-year flood events
occurred during the last half of the century
Cost of direct damage increased 5 times since 1980
Drought areas on earth surface doubled from 1970 to 2000.
World’s Major Flooding
The most vulnerable ones
Are those in developing countries, because of High poverty level Poor financial resources High dependence on ecosystem functions for
livelihood: Agriculture Fishing Tourism
Weak institutions Limited awareness re. Climate Risk Resiliency High prevalence of communicable diseases (HIV,
TB)
Philippines’ Inherent Vulnerability to Extreme Weather Variability Geographical location – an archipelago in a ring
of fire Large mountainous terrain Narrow coastal plain Interior valleys
UNDP Report on disaster: Philippines is highest in # of tropical cyclones
with average of 20 cyclones a year. Third highest in terms of people impact
Impact of Typhoon Frank on the natural resources of the Tigum-Aganan Watershed Leon – total eroded land is 660 m with 30-40
m high Wells covered with soil Aganan River changed course
San Miguel 800 meters length, eroded land, 2-6 m wide
Pavia Household water resources contaminated
Maasin Waterfalls eroded, 3 hectares wide River embankment erosion, 300 m long River width 50 m.widened 30,000 trees damaged in plantation Creeks damaged, decreasing 20% surface water
supply Observation that terraced farms have less
damage
How may RWCS help communities adapt to climate
variability User has to manage demand (discipline in use of water) Low cost Adaptable to individual situation, needed in extreme
weather variability. Control of own’s resources Encourages total community involvement Protects river & ground water ecosystems Green house gas contribution is 50% less compared
with urban piped water system/ lesser than centralized irrigation system
Stakeholders’ Assembly to raise awareness and generate recommendations
Steps in the integration process:
1. TAWMB Planning to integrate rainwater harvesting recommendations to the TigumAganan Watershed Management Plan.
2. Approval of the ammended Watershed Management Plan 2008-2010 by the Tigum-Aganan Watershed Management Board.
3. Municipal Planning Workshops in 5 municipalities to integrate stakeholders’ recommendations in the municipal development plan.
4. Approval of the Municipal Development Plan and the Annual Investment Plan
PROJECT RECOMMENDATIONS
submitted to the PROVINCIAL
LEGISLATIVE BODY
Surface Water – Storage in the Forest Restoration of damaged areas in the forest
(slopes and riverbanks). Restoration of endemic species and biodiversity
at the Maasin Watershed Soil enhancement in afforested areas and agro-
forestry areas. Use of appropriate farming methods, especially in
the upland. Institutional support: ordinances, sustainable
upkeep of the upland through payment for environmental services
Ground Water Storage Inventory and monitor ground water
extraction Limit sealed areas as part of CLUP Pre-decision as to the volume of ground
water to be used/ extracted Use artificial ground water recharge, where
needed, provide incentives and create a TWG to implement program
Institutional Support – IEC, ordinances, creation of a Ground Water TWG at IWMC
Rainwater Harvesting Integrate rainwater harvesting in municipal and
provincial development plan Create a program to promote and provide fund for
rainwater harvesting in government buildings. Require rainwater facilities for all new buildings as
part of permit requirement. Require upland farms to use appropriate farming
methods to control erosion, particularly use of terraces and ponds
Encourage farmers and provide incentives to use rainwater ponds to irrigate their farms.
Integrate Rainwater Harvesting in water and sanitation programs to provide water to households in rural and remote areas
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